June 1999 arXiv papers — page 4

Paolo Santini

Truncated Lévy flights are random walks in which the arbitrarily large steps of a Lévy flight are eliminated. Since this makes the variance finite, the central limit theorem applies, and as time increases the probability distribution of the increments becomes Gaussian. Here, truncated Lévy flights with correlated fluctuations of the variance (heteroskedastic

M. Potthoff, W. Nolting

The dynamical mean-field theory (DMFT) is employed to study the Mott transition in the semi-infinite Hubbard model at half-filling and zero temperature. We consider the low-index surfaces of the three-dimensional simple-cubic lattice and systematically vary the model parameters at the very surface. Within the DMFT the problem is self-consistently mapped onto

Didier Bozec, M. A. Howson, B. J. Hickey, Smadar Shatz

We have carried out measurements of the magnetoresistance MR(H) in the CPP (Current Perpendicular to the Plane) mode for two types of magnetic multilayers which have different layer ordering. The series resistor model predicts that CPP MR(H) is independent of the ordering of the layers. Nevertheless, the measured MR(H) curves were found to be completely diff

Julian Juhi-Lian Ting

The possibility of stochastic resonance of a quantum channel and hence the noise enhanced capacity of the channel is explored by considering the depolarizing channel. The fidelity of the channel is also considered. Although there is no clear evidence for noise enhanced capacity found, there is enhancement for the fidelity for the depolarizing channel. PACS n

Giovanni Gallavotti

The evolution of the conception of motion as composed by circular uniform motions is analyzed, stressing its continuity from antiquity to our days.

R. Scarpa, C. M. Urry, R. Falomo, A. Treves

HST observations have led to the discovery of the optical counterpart of the radio jet of PKS 2201+044, and to a detailed analysis of the optical jets of PKS 0521-365 and 3C371. At HST spatial resolution these jets are well resolved, displaying knotty morphologies. When compared with radio maps of appropriate resolution, a clear one-to-one correspondence bet

Lin Yan

We present the results of a survey which utilizes the NICMOS Camera 3 Parallel grism and imaging observations of random fields. We have identified 33 H$α$ emission-line galaxies at 0.75<z<1.9. The inferred co-moving number density of these objects is $3.3\times10^{-4} h_{50}^{3} Mpc^{-3}$, very similar to that of the bright Lyman break objects at $z \sim 3$.

Pavel Kroupa, Monika Petr, Mark McCaughrean

The frequency of low-mass pre-main sequence binary systems is significantly lower in the Trapezium Cluster than in Taurus-Auriga. We investigate if this difference can be explained through stellar encounters in dense clusters. To this effect, a range of possible models of the well observed Trapezium Cluster are calculated using Aarseth&#39;s direct N-body co

Greg L. Bryan, Marie E. Machacek

We investigate a method to determine the temperature-density relation of the intergalactic medium (IGM) at z~2-4 using quasar absorption line systems. Using a simple model combined with numerical simulations we show that there is a lower cutoff in the distribution of column density (NHI) and line width (b parameter). The location of this cutoff can be used t

Carroll O. Alley, Darryl L. Leiter, Yutaka Mizobuchi, Huseyin Yilmaz

The recent observation of the gamma ray burster GRB 990123, requiring at least two solar masses of energy in gamma radiation alone, created an energy crisis in astrophysics (Schilling 1999). We discuss a theorem which states that, of all four-dimensional curved spacetime theories of gravity viable with respect to the four classical weak field tests, only one

K. V. Johnston, S. R. Majewski, M. H. Siegel, I. N. Reid

We present a comparison of semi-analytic models of the phase-space structure of tidal debris with observations of stars associated with the Sagittarius dwarf galaxy (Sgr). We find that many features in the data can be explained by these models. The properties of stars 10-15 degrees away from the center of Sgr --- in particular, the orientation of material pe

D. G. Yakovlev, K. P. Levenfish, Yu. A. Shibanov

We study the heat capacity and neutrino emission reactions (direct and modified Urca processes, nucleon-nucleon bremsstrahlung, Cooper pairing of nucleons) in matter of supranuclear density of the neutron star cores with superfluid neutrons and protons. Various superfluidity types are analysed (singlet-state pairing and two types of triplet-state pairing, wi

S. R. Majewski, M. H. Siegel, W. E. Kunkel, I. N. Reid

As part of the Selected Areas Starcount Survey (SASS), a CCD survey to V>21, we have obtained VI photometry of two fields at b=+-40 aligned roughly with an extrapolation of the major axis of the Sagittarius (Sgr) dwarf spheroidal galaxy. Comparison of the color-magnitude diagram (CMD) for some of these fields to the CMDs of fields reflected about the Galacti

K. Sakamoto, S. K. Okumura, S. Ishizuki, N. Z. Scoville

We study the characteristics of molecular gas in the central regions of spiral galaxies on the basis of our CO(J=1-0) imaging survey of 20 nearby spiral galaxies using the NRO and OVRO millimeter arrays. Condensations of molecular gas at galactic centers with sizescales < 1 kpc and CO-derived masses M_gas(R<500pc) = 10^8 - 10^9 M_sun are found to be prevalen

Daniele Fargion, Barbara Mele

UHE neutrinos may transfer highest cosmic-rays energies overcoming $2.75K^\circ$ BBR and radio-waves opacities (the GZK cut off) from most distant AGN sources at the age of the Universe. These UHE $ν$ might scatter onto those (light and cosmological) relic neutrinos clustered around our galactic halo or nearby neutrino hot dark halo clustered around the AGN

Daniele Fargion, Andrea Aiello, Roberto Conversano

Ultra High Energy (UHE) Tau neutrino may lead to a very peculiar imprint in future underground $Km^3$ detectors in water and ice as well as in air: rarest secondary tau tracks and decay which may exceed the muon ones. Indeed Bremsstrahlung at high energy lead to longer tracks for heavier leptons. Radiation lenght grows nearly with the square of the lepton ma

Ulrich Kolb, Isabelle Baraffe

We apply the new generation of theoretical models of low-mass stars to secondaries in CVs, focussing on systems above the period gap. The models confirm that the spectral type should be a good indicator of the donor mass. The orbital period-spectral type diagram can potentially constrain the long-term mean mass transfer rate. A transfer rate that increases w

Ulrich Kolb, Isabelle Baraffe

Using improved, up-to-date stellar input physics tested against observations of low-mass stars and brown dwarfs we calculate the secular evolution of low-mass donor cataclysmic variables (CVs), including those which form with a brown dwarf donor. Our models confirm the mismatch between the calculated minimum period (Pmin ~ 70 min) and the observed short-peri

G. Lamer, A. M. Newsam, I. M. McHardy

The BL Lacertae object PKS 1413+135 is associated with a disk dominated galaxy which heavily absorbs the BL Lac nucleus at optical and X-ray wavelengths. It has been argued whether this galaxy is actually the host galaxy of PKS 1413+135 or whether the BL Lac is a background QSO, gravitationally lensed by the apparent host galaxy. We have obtained deep high r

D. L. Clements

We have conducted observations of the environment around the z=2.15 radio loud quasar 1550-269 in search of distant galaxies associated either with it or the z=2.09 CIV absorber along its line of sight. Such objects will be distinguished by their red colours, R-K>4.5. We find five such objects in a 1.5 arcmin^2 field around the quasar, with typical K magnitu

M. Radovich, U. Klaas, J. Acosta-Pulido, D. Lemke

We present the spectral energy distribution (SED) between 10 and 200 micron obtained for the prototype Narrow-Line X-Ray Galaxy NGC 7582 with ISOPHOT, the photometer on board the Infrared Space Observatory. The emission is spatially extended and we separated for the first time the nuclear and extranuclear infrared SEDs. The nuclear luminosity is dominated by

Gabriel W. Pratt, B. J. M. Hassall, T. Naylor, Janet H. Wood

We present ROSAT X-ray and optical light curves of the 1994 February superoutburst of the eclipsing SU UMa dwarf nova OY Carinae. There is no eclipse of the flux in the ROSAT HRI light curve. Contemporaneous `wide B&#39; band optical light curves show extensive superhump activity and dips at superhump maximum. Eclipse mapping of these optical light curves re

M. Kramer, C. Lange, D. R. Lorimer, D. C. Backer

In this paper we present the first observations of a large sample of millisecond pulsars at frequencies of 2.7 GHz and 4.9 GHz. Our new flux measurements extend the known spectra for millisecond pulsars to the highest frequencies to date. The coverage of more than a decade of radio spectrum allows us for the first time to search for spectral breaks as so oft

Michael Thierbach, Ulrich Klein, Richard Wielebinski

We present the current status of radio observations of several clusters of galaxies done with the 100-m telescope Effelsberg. The purpose of this still ongoing project is to obtain new sensitive single-dish measurements of large extended diffuse radio sources in these clusters. The use of a single-dish is required to recover all the flux. In this paper we pr

M. Micono, N. Zurlo, S. Massaglia, A. Ferrari

We calculate the temporal evolution of distributions of relativistic electrons subject to synchrotron and adiabatic processes and Fermi-like acceleration in shocks. The shocks result from Kelvin-Helmholtz instabilities in the jet. Shock formation and particle acceleration are treated in a self-consistent way by means of a numerical hydrocode. We show that in

C. A. L. Bailer-Jones, R. Mundt

We have undertaken a differential photometric I band search for variability in three Pleiades brown dwarfs and three very low mass field L dwarfs. Analysis of the resultant time series for the Pleiades brown dwarfs (Teide 1, Calar 3, Roque 11) gives no evidence for variability (above 99% confidence) greater than 0.05 mags in any of these objects on timescale

Roberto Soria, Kinwah Wu, Helen Johnston

We carried out spectroscopic observations of the candidate black-hole binary GX339-4 during its low-hard and high-soft X-ray states, in 1997 and 1998 respectively. We have found that the spectrum is dominated by emission lines of neutral elements with asymmetric, round-topped profiles in the low-hard state (probably due to a dense matter outflow from an infl

Bhaswati Mookerjea, S. K. Ghosh

Embedded Young Stellar Objects (YSO) in dense interstellar clouds is treated self-consistently to understand their spectral energy distributions (SED). Radiative transfer calculations in spherical geometry involving the dust as well as the gas component, have been carried out to explain observations covering a wide spectral range encompassing near-infrared t

Irapuan Rodrigues, Horacio Dottori, Elias Brinks, I. Felix Mirabel

We present optical spectroscopy, B, V, R and I CCD photometry and VLA neutral hydrogen observations of the interacting quartet NGC 6845, also know as Klemola 30. NGC 6845 A, the dominant component, sports a broad and bright tidal bridge and a faint tidal tail, which bifurcate. The tidal bridge has a (B-I) color bluer than that of NGC 6845 A inner disk. Five

Daniele Fargion

Gamma Ray Bursts as recent GRB990123 and GRB990510 are observed to occur in cosmic volumes with a corresponding output reaching, for isotropic explosions, energies as large as two solar masses annihilation. These energies are underestimated because of the neglected role of comparable ejected neutrinos bursts. These extreme power cannot be explained with any

T. A. Ensslin, Kronberg, R. A. Perley, N. E. Kassim

We report on an ongoing project to map a 15 degree x 15 degree region in Coma Berenices with the new 74 MHz receiver system of the VLA. The field is centered on the Coma cluster of galaxies. Coma Berenices has been observed in all VLA configurations, which allowed us to resolve several hundred point sources with 35 arcsecond resolution. We have successfully

Harry Paul, Mladen Pavicic

We propose a realistic device for detecting objects almost without transferring a single quantum of energy to them. The device can work with an efficiency close to 100% and relies on two detectors counting both presence and absence of the objects. Its possible usage in performing fundamental experiments as well as possible applications are discussed.

Glennys R. Farrar, Tsvi Piran

The apparent lack of suitable astrophysical sources for the observed highest energy cosmic rays (UHECRs) within $\approx 20$ Mpc is the &#34;GZK Paradox&#34;. We constrain representative models of the extra-galactic magnetic field structure by Faraday Rotation measurements; limits are at the $μ$G level rather than the nG level usually assumed. In such fields

Yuji Ohta

In general, Whitham dynamics involves infinitely many parameters called Whitham times, but in the context of N=2 supersymmetric Yang-Mills theory it can be regarded as a finite system by restricting the number of Whitham times appropriately. For example, in the case of SU(r+1) gauge theory without hypermultiplets, there are r Whitham times and they play an e

Ian Agol

We show that for a hyperbolic knot complement, all but at most 12 Dehn fillings are irreducible with infinite word-hyperbolic fundamental group.

Alexander Volya, Scott Pratt, Vladimir Zelevinsky

We consider an ``oriented&#39;&#39; chiral condensate produced in the squeezed states of the effective field theory with time- and space-dependent pion mass parameter. We discuss the general properties of the solution, identifying condensate modes and determining the resulting pion distributions. The implementation of the dynamics in the form of sudden pertu

W. C. Haxton, C. -L. Song

The shell model is the standard tool for addressing the canonical nuclear many-body problem of nonrelativistic nucleons interacting through a static potential. We discuss several of the uncontrolled approximations that are made in this model to motivate a different approach, one based on an exact solution of the Bloch-Horowitz equation. We argue that the nec

Moti Gitik

Let kappa be the limit of <kappa_n : n<omega> (1) if each kappa_n carries an extender of the length of the first Mahlo above kappa_n, then for every ld above kappa there is a generic extension with power of kappa above ld. (2) if each kappa_n carries an extender of the length of the first fixed point of the aleph function above kappa_n of order n then for ev

Vadim Schechtman

A report at Arbeitstagung, June 1999, Bonn, on the joint work with V.Gorbounov, F.Malikov and A.Vaintrob.

Ian Agol

In this paper, we find lower bounds for volumes of hyperbolic 3-manifolds with various topological conditions. Let V_3 = 1.01494 denote the volume of a regular ideal simplex in hyperbolic 3-space. As a special case of the main theorem, if a hyperbolic manifold M contains an acylindrical surface S, then Vol(M)>= -2 V_3 chi(S). We also show that if beta_1(M)>=

Janos Polonyi

A subjective and incomplete list of interesting and unique features of the deconfinement phase transition is presented. Furthermore a formal similarity of the density matrix of the Aharonov-Bohm system and QCD is mentioned, as well.

Jaume Guasch

In this Thesis we have investigated some effects appearing in top quark observables in the framework of the Minimal Supersymmetric Standard Model (MSSM). We have computed the radiative corrections to some top quark observables, using the on-shell renormalization scheme, and with a physically motivated definition of the tan(beta) parameter. Introductory chapt

Yannick Meurice

We present two Fermi-Bose models with an approximate supersymmetry and which can be solved with great accuracy using the renormalization group method. The bosonic parts of these models consist in Dyson&#39;s hierarchical model with one and two scalar components respectively. We discuss the question of the perturbative cancellation of divergences and compare

NuTeV Collaboration, T. Adams, A. Alton, S. Avvakumov

The NuTeV experiment uses neutrino deep-inelastic scattering from separate neutrino and anti-neutrino beams to study the structure of the nucleon. Charged-current production of charm is sensitive to the strange content of the nucleon while neutral-current charm production probes the charm content. Preliminary analyses of both topics are presented along with

NuTeV Collaboration, T. Adams, A. Alton, S. Avvakumov

Neutrino deep-inelastic scattering provides a means to study both the strange and charm content of the nucleon. The NuTeV experiment (Fermilab E-8Neutrino deep-inelastic scattering provides a means to study both the strange and charm content of the nucleon. The NuTeV experiment (Fermilab E-815) takes full advantage of separated neutrino and anti-neutrino bea

Nikolai V. Brilliantov, Thorsten Poeschel

We analyze the velocity distribution function of force-free granular gases in the regime of homogeneous cooling when deviations from the Maxwellian distribution may be accounted only by leading term in the Sonine polynomial expansion. These are quantified by the magnitude of the coefficient $a_2$ of the second term of the expansion. In our study we go beyond

B. E. Vugmeister, H. Rabitz

We have developed a dynamical model for the dielectric response in relaxor ferroelectrics which explicitly takes into account the coexistence of the critical slowing down and glassy freezing. The application of the model to the experiment in PMN allowed for the reconstruction of the nonequilibrium spin glass state order parameter and its comparison with the

C. Sanchez-Fernandez, A. J. Castro-Tirado, H. W. Duerbeck, L. Mantegazza

We report here optical observations during the September/October 1998 outburst of the black hole candidate XTE J1550-564. CCD photometry was obtained for the optical counterpart with the 0.9m Dutch telescope at La Silla since the onset of this event. We analysed 211 U, V and i frames, from Sep 10 to Oct 23. Stochastic flaring activity was observed on Sep 11-

F. Thevenin, T. P. Idiart

We report new statistical equilibrium calculations for Fe I and Fe II in the atmosphere of Late-Type stars. We used atomic models for Fe I and Fe II having respectively 256 and 190 levels, as well as 2117 and 3443 radiative transitions. Photoionization cross-sections are from the Iron Project. These atomic models were used to investigate non-LTE effects in i

Yoshiaki Taniguchi, Naohisa Anabuki

The electron scattering region (ESR) is one of important ingredients in Seyfert nuclei because it makes possible to observe the hidden broad line region (hereafter HBLR) in some type 2 Seyfert nuclei (hereafter S2s). However, little is known about its physical and geometrical properties. Using the number ratio of S2s with and without HBLR, we investigate sta

Francesc Perera

Given a unital ring $R$ and a two-sided ideal $I$ of $R$, we consider the question of determining when a unit of $R/I$ can be lifted to a unit of $R$. For the wide class of separative exchange ideals $I$, we show that the only obstruction to lifting invertibles relies on a K-theoretic condition on $I$. This allows to extend previously known index theories to

Massimo Di Pierro, Chris T Sachrajda, Chris Michael

A possible explanation of the apparent disrepency between the theoretical prediction and experimental measurement of the ratio of lifetimes $τ(Λ_b)/τ(B_d)$ is that ``spectator effects&#39;&#39;, which appear at $O(1/m_b^3)$ in the heavy quark expansion, contribute significantly. We investigate this possibility by computing the corresponding operator matrix e

E. Kiritsis

A D3-brane probe in the context of AdS/CFT correspondence at finite temperature is considered. The supergravity predictions for the physical effective couplings of the world-volume gauge theory of the probe brane are compared to those calculated in one-loop perturbation theory in the thermal gauge theory. It is argued that when the Higgs expectation value is

Morimitsu Tanimoto

We have discussed the search of the genuine CP violation in a neutrino factory, in which well known neutrino beams are provided by a high intensity muon storage ring. Both $ΔP(\n_\a \Ar \n_\b)$ and CP odd asymmetry $A_{CP}$ in neutrino oscillations are investigated by taking account of the atmospheric neutrino data and the solar neutrino data. If the large m

Hungchong Kim

In QCD sum rules with external fields, the double dispersion relation is often used to represent the correlation function. In this work, we point out that the double spectral density, when it is determined by successive applications of the Borel transformation, contains the spurious terms which should be kept in the subtraction terms in the double dispersion

James P. Crutchfield, David P. Feldman, Cosma Rohilla Shalizi

We critique the measure of complexity introduced by Shiner, Davison, and Landsberg in Ref. [1]. In particular, we point out that it is over-universal, in the sense that it has the same dependence on disorder for structurally distinct systems. We then give counterexamples to the claim that complexity is synonymous with being out of equilibrium: equilibrium sy

A. D. Miller, R. Caldwell, M. J. Devlin, W. B. Dorwart

We report on a measurement of the angular spectrum of the CMB between $l\approx 100$ and $l\approx 400$ made at 144 GHz from Cerro Toco in the Chilean altiplano. When the new data are combined with previous data at 30 and 40 GHz, taken with the same instrument observing the same section of sky, we find: 1) a rise in the angular spectrum to a maximum with $δT

Jean-Pierre Amiet, Stefan Weigert

Non-orthogonal bases of projectors on coherent states are introduced to expand hermitean operators acting on the Hilbert space of a spin s. It is shown that the expectation values of a hermitean operator A in a family of (2s+1)(2s+1) spin-coherent states determine the operator unambiguously. In other words, knowing the Q-symbol of A at (2s+1)(2s+1) points on

M. Yu. Kuchiev, V. N. Ostrovsky

Fully quantum treatment explicitly presents the high harmonic generation as a three-step process: (i) above threshold ionization (ATI) is followed by (ii) electron propagation in a laser-dressed continuum. Subsequently (iii) stimulated (or laser assisted) recombination brings the electron back into the initial state with emission of a high-energy photon. Con

Francesc Perera

In this paper we investigate the extremal richness of the multiplier algebra $M(A)$ and the corona algebra $M(A)/A$, for a simple C*-algebra $A$ with real rank zero and stable rank one. We show that the space of extremal quasitraces and the scale of $A$ contain enough information to determine whether $M(A)/A$ is extremally rich. In detail, if the scale is fi

E. Ballico, E. Gasparim

We suggest an effective procedure to calculate numerical invariants for rank two bundles over blown-up surfaces. We study the moduli spaces M_j of bundles on the blown-up plane splitting over the exceptional divisor as O(j)+O(-j). We use the numerical invariants to give a topological decomposition of M_j.

A. Liguori, M. Mintchev, L. Pilo

An operator formalism for bosonization at finite temperature and density is developed. We treat the general case of anyon statistics. The exact $n$-point correlation functions, satisfying the Kubo-Martin-Schwinger condition, are explicitly constructed. The invariance under both vector and chiral transformations allows to introduce two chemical potentials. In

V. A. Saleev

In the framework of the leading order of perturbative QCD and the nonrelativistic quark-diquark model of baryons we have obtained fragmentation function for c-quark to split into Omega_{ccc} baryon. It is shown that at LHC one can expect 3.5 10^3 events with Omega_{ccc} at p_t>5 GeV/c and -1<y<1 per year.

S. Catterall, E. Mottola

We verify that summing 2D DT geometries correctly reproduces the Polyakov action for the conformal mode, including all ghost contributions, at large volumes. The Gaussian action is reproduced even for c=10, well into the branched polymer phase, which confirms the expectation that the DT measure is indeed correct in this regime as well.

Giampiero Esposito, Cosimo Stornaiolo

The Einstein theory of general relativity provides a peculiar example of classical field theory ruled by non-linear partial differential equations. A number of supplementary conditions (more frequently called gauge conditions) have also been considered in the literature. In the present paper, starting from the de Donder gauge, which is not conformally invari

Vladimir B. Braginsky, Mikhail L. Gorodetsky, Farid Ya. Khalili, Kip S. Thorne

A description and analysis are given of a ``speed meter&#39;&#39; for monitoring a classical force that acts on a test mass. This speed meter is based on two microwave resonators (``dual resonators&#39;&#39;), one of which couples evanescently to the position of the test mass. The sloshing of the resulting signal between the resonators, and a wise choice of

Edith Hemaspaandra

In the early 1980s, Selman&#39;s seminal work on positive Turing reductions showed that positive Turing reduction to NP yields no greater computational power than NP itself. Thus, positive Turing and Turing reducibility to NP differ sharply unless the polynomial hierarchy collapses. We show that the situation is quite different for DP, the next level of the

M. I. Katsnelson, A. V. Trefilov

A microscopic picture of the ``preparation&#39;&#39; of a crystal to the transition to liquid state at the approach to melting temperature is proposed. Basing on simple crystallogeometric considerations and the analysis of the computational results for corresponding anharmonic characteristics an evaluation is given for the magnitude of atomic displacements l

Victor Barzykin, Lev P. Gor&#39;kov

We critically investigate the model of a doped excitonic insulator, which recently has been invoked to explain some experimental properties of the ferromagnetic state in Ca_{1-x}La_xB_6. We demonstrate that the ground state of this model is intrinsically unstable towards the appearance of a superstructure. In addition, the model would lead to a phase separat

Julyan H. E. Cartwright, Diego L. Gonzalez, Oreste Piro

We apply results from nonlinear dynamics to an old problem in acoustical physics: the mechanism of the perception of the pitch of sounds, especially the sounds known as complex tones that are important for music and speech intelligibility.

J. C. Augereau, A. M. Lagrange, D. Mouillet, J. C. B. Papaloizou

We investigate in details the properties of the disk surrounding the 8 Myr old star HR 4796A, one of the few stars bringing precious clues to better understand the scenario which lead to planetary system formation. We propose a model able to reproduce all the available observations : the full spectral energy distribution from the mid-infrared to the millimet

M. A. Aloy, J. M. Ibanez, J. M. Marti J. L. Gomez, E. Muller

We have performed high-resolution 3D simulations of relativistic jets with beam flow Lorentz factors up to 7, a spatial resolution of 8 cells per beam radius, and for up to 75 normalized time units to study the morphology and dynamics of 3D relativistic jets. Our simulations show that the coherent fast backflows found in axisymmetric models are not present i

C. L. Taylor, S. Huettemeister, U. Klein, A. Greve

We present CO (1-0) and (2-1) observations of the dwarf starburst galaxy NGC 1569 with the IRAM interferometer on Plateau de Bure. We find the CO emission is not spatially associated with the two super star clusters in the galaxy, but rather is found in the vicinity of an HII region. With the resolution of our data, we can resolve the CO emission into five d

S. Orito, T. Maeno, H. Matsunaga, K. Abe

The energy spectrum of cosmic-ray antiprotons has been measured in the range 0.18 to 3.56 GeV, based on 458 antiprotons collected by BESS in recent solar-minimum period. We have detected for the first time a distinctive peak at 2 GeV of antiprotons originating from cosmic-ray interactions with the interstellar gas. The peak spectrum is reproduced by theoreti

V. Karas, O. Semerak, F. de Felice

Three recent papers have been collected here, discussing the possibility and properties of periodic modulation of a signal from accreting black holes surrounded by orbiting clumps of gas.

Harvey B. Richer

The microlensing experiments in the direction of the LMC seem to be indicating that about 60% of the dark matter in the Galactic halo is tied up in objects whose masses are about half the mass of the Sun. This mass is a natural one for old white dwarfs although other possibilities do exist. Using a grid of newly constructed models of cooling white dwarfs whi

C. J. Miller, M. J. Ledlow, D. J. Batuski

We present the results from two-point spatial correlation analyses on X-ray confirmed northern Abell clusters. The cluster samples are subsets of a volume-limited ROSAT All-Sky Survey study of 294 Abell clusters of which 240 are X-ray luminous. We examined magnitude- and volume-complete samples for differences according to richness and X-ray luminosity. For

P. L. Hammersley, M. Cohen, F. Garzon, T. Mahoney

We analyse the stellar content of almost 300 deg^2 of the sky close to the Galactic plane by directly comparing the predictions of the SKY model (Cohen 1994,1995; Wainscoat et al. 1992) with star counts taken from the Two Micron Galactic plane Survey (TMGS: Garzon et al. 1993). Through these comparisons we can examine discrepancies between counts and model a

Tsuyoshi Hamada, Toshiyuki Fukushige, Atsushi Kawai, Junichiro Makino

We have developed PROGRAPE-1 (PROgrammable GRAPE-1), a programmable multi-purpose computer for many-body simulations. The main difference between PROGRAPE-1 and &#34;traditional&#34; GRAPE systems is that the former uses FPGA (Field Programmable Gate Array) chips as the processing elements, while the latter rely on the hardwired pipeline processor specialize

Daniel Dumitru, Satyanarayan Nandi

We make a detailed study of the unification of gauge couplings in the MSSM with large extra dimensions. We find some scenarios where unification can be achieved (with the strong coupling constant at the Z mass within one standard deviation of the experimental value) with both the compactification scale and the SUSY breaking scale in the few TeV range. No enl

Csaba Csaki, Michael Graesser, Christopher Kolda, John Terning

We examine the cosmology of the two recently proposed scenarios for a five dimensional universe with localized gravity. We find that the scenario with a non-compact fifth dimension is potentially viable, while the scenario which might solve the hierarchy problem predicts a contracting universe, leading to a variety of cosmological problems.

Thomas Schaefer, Frank Wilczek

We study color superconductivity in QCD at asymptotically large chemical potential. In this limit, pairing is dominated by perturbative one-gluon exchange. We derive the Eliashberg equation for the pairing gap and solve this equation numerically. Taking into account both magnetic and electric gluon exchanges, we find $Δ\sim g^{-5}\exp(-c/g)$ with $c=3π^2/\sq

Boris Podobnik, Plamen Ch. Ivanov, Youngki Lee, H. Eugene Stanley

We develop a scale-invariant truncated Lévy (STL) process to describe physical systems characterized by correlated stochastic variables. The STL process exhibits Lévy stability for the probability density, and hence shows scaling properties (as observed in empirical data); it has the advantage that all moments are finite (and so accounts for the empirical sc

Xiaoqun Wang, Lu Yu

Using the recently developed transfer-matrix renormalization group method, we have studied the thermodynamic properties of two-leg antiferromagnetic ladders in the magnetic field. Based on different behavior of magnetization, we found disordered spin liquid, Luttinger liquid, spin-polarized phases and a classical regime depending on magnetic field and temper

Tao Han, Danny Marfatia, Ren-Jie Zhang

We study in some detail the next-to-minimal supersymmetric standard model with gauge mediation of supersymmetry breaking. We find that it is feasible to spontaneously generate values of the Higgs mass parameters $μ$ and $B_μ$ consistent with radiative electroweak symmetry breaking. The model has a phenomenologically viable particle spectrum. Messenger sneutr

L. Mersini

We use the model of L. Randall et al to investigate the stability of allowed quantum field configurations. Firstly, we find that due to the topology of this 5 dimensional model, there are 2 possible configurations of the scalar field, untwisted and twisted. They give rise to two types of instability. Secondly, when allowed to interact in the 3-brane, the unt

Caroline Santos, Ruth Gregory

We study analytically black holes pierced by a thin vortex in dilatonic gravity for an arbitrary coupling of the vortex to the dilaton in an arbitrary frame. We show that the horizon of the charged black hole supports the long-range fields of the Nielsen-Olesen vortex that can be considered as black hole hair for both massive and massless dilatons. We also p

Pavel Ivanov

We consider the generation of the scalar mode of the metric perturbations during preheating stage in a two field model with the potential $V(ϕ, χ)= {m^{2}ϕ^{2}\over 2}+{g^{2}ϕ^{2}χ^{2}\over 2}$. We discuss two possible sources of such perturbations: a) due to the coupling between the perturbation of the matter field $δχ$ and the background part of the matter

D. Bailin, G. V. Kraniotis, A. Love

The phenomenological implications of the M-theory limit in which supersymmetry is broken by the F-terms of five-brane moduli is investigated. In particular we calculate the supersymmetric spectrum subject to constraints of correct electroweak symmetry breaking. We find interesting differences especially in the squark sector compared with $M$-theory scenarios

L. Beaulieu, K. Kwiatkowski, W. -c. Hsi, T. Lefort

Excitation-energy distributions have been derived from measurements of 5.0-14.6 GeV/c antiproton, proton and pion reactions with $^{197}$Au target nuclei, using the ISiS 4$π$ detector array. The maximum probability for producing high excitation-energy events is found for the antiproton beam relative to other hadrons, $^3$He and $\bar{p}$ beams from LEAR. For

R. Aleksan, M. Zito, A. Le Yaouanc, L. Oliver

We compute the inclusive decay rates $b \to D_s^-(D^{*-}_s) c$ including lowest order QCD corrections on the quark legs, and compare with existing data. Unlike the short distance QCD corrections, that are of higher order, these corrections are of order $α_s$. In the on-shell renormalization scheme and for $α_s(m_b) \cong 0.2$ we find a correction of -10% to

R. Aleksan, M. Zito, A. Le Yaouanc, L. Oliver

We propose the determination of the CKM matrix element $|V_{ub}|$ by the measurement of the spectrum of $B \to D_s^+ X_u$, dominated by the spectator quark model mechanism $\bar{b} \to D_s^{(*)+} \bar{u}$. The interest of considering $B \to D_s^+X_u$ versus the semileptonic decay is that more than 50 % of the spectrum for $B \to D_s^+ X_u$ occurs above the k

Xavier Waintal, Giuliano Benenti, Jean-Louis Pichard

Extending finite size scaling theory to the many body ground state, one finds that Coulomb repulsion can drive a system of spinless fermions in a random potential from the Anderson insulator (Fermi glass of localized states) towards a new extended phase in dimension $d=2$. The transition occurs at a Coulomb energy to Fermi energy ratio $r_s \approx 4$, where

Junichi Noaki, Yusuke Taniguchi

We estimate the lattice artifacts in loop correction perturbatively for domain-wall QCD with infinite number of extra flavors. We find that there appear no ${\cal O}(a)$ errors in renormalization factors of quark wave function, mass and quark bilinear operators at one and two loop level with off-shell quark momentum. Our proof is based on even or oddness of

S. Dickmann

The absorption of bulk acoustic phonons in a two-dimensional (2D) GaAs/AlGaAs heterostructure is studied (in the clean limit) where the 2D electron-gas (2DEG), being in an odd-integer quantum-Hall state, is in fact a spin dielectric. Of the two channels of phonon absorption associated with excitation of spin waves, one, which is due to the spin-orbit (SO) co

S. Dickmann, Y. Levinson

Relaxation of collective plasmon inter-Landau-level excitation is determined by emission of LO-phonons or by Auger-like processes when this emission is suppressed off the magneto-phonon resonance conditions. The decay of &#34;one-cyclotron&#34; magneto-plasmons with wave-vectors near the roton minimum is studied under the condition of filling $ν=1$. Some fea

Massimo Ricotti, Nickolay Y. Gnedin, J. Michael Shull

We develop a method to extract the &#34;effective equation of state&#34; of the intergalactic medium from the doppler b parameter distribution of the low-density Lyman-alpha forest. We test the method on numerical simulations and then apply it to published observations of the Lyman-alpha forest at redshifts z from 0 to 4. We find that the effective equation

Ilka Brunner, Michael R. Douglas, Albion Lawrence, Christian Romelsberger

We study D-branes on the quintic CY by combining results from several directions: general results on holomorphic curves and vector bundles, stringy geometry and mirror symmetry, and the boundary states in Gepner models recently constructed by Recknagel and Schomerus, to begin sketching a picture of D-branes in the stringy regime. We also make first steps tow

J. Dzubiella, M. Schmidt, H. Loewen

Using computer simulations we investigate the microscopic structure of the singular director field within a nematic droplet. As a theoretical model for nematic liquid crystals we take hard spherocylinders. To induce an overall topological charge, the particles are either confined to a two-dimensional circular cavity with homeotropic boundary or to the surfac

J. Blaschke, M. Brack

We study the magnetoconductance of electrons through a mesoscopic channel with antidots. Through quantum interference effects, the conductance maxima as functions of the magnetic field strength and the antidot radius (regulated by the applied gate voltage) exhibit characteristic dislocations that have been observed experimentally. Using the semiclassical per